When I was trying to do this I also kept a little bit of paper in my pocket with a sentence on it that I got into the habit of pulling out and reading every now and then IRL, in the hopes that when I then got it out and read it in a dream and the words wouldn't make sense or would say something different (this happens), it'd act as a sort of trigger/reminder that I'm dreaming. It only ended up doing the job for me once or twice to be honest, but others found it way more helpful.

There's more disruptive stuff you can do like set alarms for after one REM cycle because as you've already noticed it's easier to slip into a lucid dream (and more importantly remember it) if you're only sleeping lightly. But you gotta ask yourself what you want to sacrifice in the pursuit of lucidity.

Also yeah as has been mentioned a dream journal is supposed to be key to help strengthen your memory of all dreams (no point lucid dreaming if you can not/barely remember it etc.)

Oh and watch "Waking Life" one night before bed - cool movie IIRC, and nothing like dreaming about a movie about lucid dreams to raise the question in your sleep "wait am I dreaming right now then?"